As electronics evolve, there is an increased need for miniature switches that are provided on semiconductor substrates along with other semiconductor components to form various types of circuits. These miniature switches often act as relays, and are generally referred to as micro-electro-mechanical system (MEMS) switches. MEMS switches generally include a moveable portion such as a cantilever, which has a first end anchored to the semiconductor substrate, and a second free end having a cantilever contact. When the MEMS switch is activated, the cantilever moves the cantilever contact against a substrate contact on the semiconductor substrate and under the cantilever contact.
In many applications, numerous MEMS switches are required for a given circuit topology. For example, a radio frequency (RF) front-end section of a cellular telephone may have ten or more MEMS switches to aid in receiving, mixing, and transmitting various signals. Unfortunately, MEMS switches are generally formed as discrete components that reside alone or with other MEMS switches in a dedicated module. The circuitry employing the MEMS switches is generally formed on another semiconductor structure. The module or modules for the MEMS switches are mounted to the semiconductor structure to complete the circuitry that requires the MEMS switches. Thus, the MEMS switches are formed on discrete modules that are separate from the semiconductor structure that contains the circuitry associated with the MEMS switches.
By not being able to form the MEMS switches at the same time and using the same processes used to form the associated circuitry, the cost and size of modules containing the circuitry significantly increase. In addition to the time and effort required to mount the discrete MEMS switches to a particular semiconductor structure that contains the associated circuitry, the packaging required to protect the MEMS switches and connect the MEMS switches to the semiconductor structure often takes up significantly more space than the MEMS switches themselves.
Accordingly, there is a need for an effective and efficient way to form MEMS switches on a semiconductor structure along with the circuitry associated with the MEMS switches.